Consumer cleaning products incorporating a color change feature are desirable to an end user. The color change may indicate that the product is effectively working. A color change may also indicate that the product has reached the end of its effective in-use lifetime. Color changes may connote other meaningful signals to the user, such as providing a synergistic aesthetic visual signal in tandem with the reduction of product fragrance intensity.
Self-adhering gel compositions are known for use as continuous hard surface cleaning systems, such as for flush toilets, wherein water passes over the gel composition with each flush of the toilet, thereby eroding or dissolving a minor amount of the composition with each flush and distributing cleaning ingredients to the toilet water and toilet bowl surface above and/or below the water line depending on the composition. Self-adhering gel compositions are described in U.S. Pat. No. 6,667,286 B1 and U.S. Patent Application Publication Nos. 2008/0255017 A1 and 2009/0215661 A1, the disclosures of this patent and each of these applications being incorporated herein by reference.
U.S. Pat. No. 6,667,286 B1 and U.S. Patent Application Publication No. 2008/0255017 A1 disclose the incorporation of a dye or colorant into the gel compositions. However, no information is provided as to the selection of any specific dye or colorant. Further, no color-changing system of any type is disclosed. The self-adhering gel compositions disclosed are used as continuous hard surface cleaning systems where, in use, water periodically passes over the gel composition. The compositions are especially applicable as self-adhesive, continuous, self-cleaning sanitary compositions for use in flush toilets and urinals.